Pi is the ratio of the circumference of a circle to its diameter. It’s an important foundation of mathematics, most importantly in geometry, physics and engineering.

3.14, pi’s first three digits, are well known but the rest is infinitely long. Extending the number is no leisurely pastime. It’s an extremely difficult challenge since the sequence follows no set pattern.

Mathematician James Grime says that just 39 digits of pi is enough to calculate the circumference of the known universe, and NASA’s Jet Propulsion lab only uses 15 digits to calculate interplanetary travel. Pi is being used in many NASA pursuits, including landing on Mars, discovering new inhabitable planets and tracking asteroid movements.

Iwao found the digits with the help of Google Cloud in the Japanese city of Osaka, some 400km west of Tokyo, where she works as a developer and advocate. The calculation was completed with 25 virtual machines in 121 days and took up 170TB of data. To put that into perspective: 1TB holds about 200,000 songs.

The Guinness World Records certified Iwao’s milestone on Wednesday, making her the third woman to set a world record for calculating pi.

Iwao said she has been fascinated with pi since she was 12, writes Google. “When I was a kid, I downloaded a program to calculate pi on my computer,” she says. “At the time, the world record holders were Yasumasa Kanada and Daisuke Takahashi, who are Japanese, so it was really relatable for me growing up in Japan.”